Electrically-heated tempering bath



June l2. 1928.

- L. P. HYNEs ELECTRICALLY HEATED TEMPERING BATH Filed Aug. 6, 1926'lllllllllllllllll |01 lllll IIIIII G ,..ll Llllllllfllll Smvemtoz Le: P.HYNES SMM/mut Patented June 12, 1928.

UNITED f STATES l 1,673,567 PATENT OFFICE.

LEE P. AHYNES, F ALBANY,` NEW YORK, ASSIGNOR TO HYNES & COX ELECTRICCOR- PORATION, OF ALBANY, NEW YORK, AICORPQRATION OF NEW YORK.

ELECTRICALLY-HEATED TEMPERING BATH.

Application filed August 6, 1926. Serial No. 127,645.

For a detailed description of the present form of my invention,reference may be had [to the following specification and to theaccompanying drawingsv forming apart thereof, wherein Fig. l is alongitudinal section of my device on the line 11v of Fig. 2;

Fig. 2 is a plan view with the cover removed;

Fig. 3 is a diametric section of the heater with the coil in elevationtaken on the lines 3 3 of Fig. 4;

Fig. 4 is a plan view of Fig. 3 with the lcover removed.

My invention relates fundamentally to a method of heating electrically aliquid, such as the oil bath used for the tempering and heat treatmentof many forms of metallic articles, wherein it is desired to maintainthe y oil at a given temperature and in a clean Y condition. Heretofreit has been the practice to heat the oil electrically by placing i-n thebody of oil an ordinary heater-coil suitably insulated and protected.The defect of this method is that for a considerable body of oil ahightemperaturelin the heater-coil is employed, the surface area of thecoill being relatively small and intensely hot;

. hence the oil will often carbonize on the surface of the heater and.in time cause the heater to burn out 'because of inadequate radiation,while the `oil becomes blackened and damaged by overheating. 'Also theoil "nearthe heater' is much hotter than that 35V farther away becausethe convection currents `f in the oil are very slow. Forsuch operationsas the drawing of steel tempered tools'` uniformity of temperature inall parts of the oil bath is essential." 'Yet such uniformity of 40temperature is not 'attainable in said prior arrangement, not onlybecause of the unequal,l

,` distance of different parts of the oil from the electric heater," butlalso', because of the local chilling of the oil by the cold steel whenrstfimmersed. "Nor is it possible to elimi!r nate this spotty heating bymechanically stirring thebody of oil, as is also attempted in the prior'arty because of the imperfect convection of heat by the oil. I have suc-.59 cessfully overcome these troubles yby the method of constantlydrawing olf 'the oily c from the bath,forcing it in a stream through acoiled pipe which is electrically heated and then returning it to thebath. Preferably 551th@ ai is separate frein the' man fsuA that ne partofthe oil will receive extra heat by .Contact with the outside surfaceof the coil 1n distinction from the normal heat which every part of theoil receives from the interior surface of the coil in it journeytherethrough. Moreover, the forced flow through the coiled pipe, whichis a pipe of circular cross section, produces a swirling action of theoil that keeps all parts thereof constantl Y and thoroughlyintermingled. There y uniformity of temperature is promoted by themutual convection of the inter l mingled parts, as wellas by theiruniform exposure to the` heating agency. I have also devised otherfeatures that will be described hereinafter. f

Referring to the drawing, A represents a tank which, lin this case, isrectangular in form and provided with double walls that enclose betweenthem the heat-insulating material B. A longitudinal L-shaped parti-Vtion() divides the interior space into two compartments of which thelarger one, of L-shaped contour, may be termed the inflow compartmentand the smaller one, of plain rectangular shape, the outflowcompartment. Near the bottom'of the latter is a horizontal screen D;while in the former, also near the bottom is a Slow-moving conveyor'belt E` which is kept in constant mot-ion by any suitable external-motive power, as is indicated by the crank-handle F. The oil enters bythe upright vinflow pipe G which passes downV into the inflowcompartment to a header G2 from which two branch pipes g,

g extends out horizontally underneath the upper course'o'f the conveyorbeltl E. y The header G2 and the branch pipes g, g, which constitute adistributor for the incoming oil, are perforated with holes at intervalsthroughwhich thevoil enters the inflow compartment inV distributed jets.These jets are vmorey numerous at and near the header be cause rit is atthat end of the compartment that the `cold articles to be treated areintroduced. For example, the articles may be placed in a wire basket H,shownin Fig. l, and lowered into the oil, through an uplifted lid I onthe top of the tank, and there placed on the left hand end of theconveyor belt. The ybelt carries them slowly through the. oil to theright-hand end ofthe compartment, where the basket with its Vcphtentsisv lifted out through anwoverlylng cover-opening having a li. il.

The basket f from. 'it any4 foreign matter.

an inch indepth, througli'whi'ch"the oil from vthe inflow compartmentoverflows into the outflow compartment, theremtalling down lon `the'aforesaid screen D which removes After passing through screen D to thebottomV of the com- .partmenathe oil is sucked up the outow pipe-K,through the agency ofpump VP'and,V delivered to the electric. heater.

The vertical tube T- in the inflow compartment is openf'at both endsVfor thereception of a thermometer equipped to serve vas a thermostat.v-

,-fThe heater-is lshown inflfigs. Sande.y `It hasa cylindrical casing,with double walls enclosingheatinsulation B2, and areniova- {.b'leIvcover O. Within this casing acentral metal frame M,c`arries` on itsouter4 periphery a series of vertical heater elements R, lt, such, forexample, as-are shownzin my f Patent-No.A 1,549,773, grantedAugust 181925. Surrounding-'theseand inside, the ,an-

f nularspace within the casing wall is arpipecoil, L through which theoil: is circulated by pump As is `indicated by dottedlines,VY thefintake of rthe ypump is connected with the outflow pipe of theoil-tank, `while the inflow pipe of the. tank draws from thel outflowterminal of. theLcoil M. The

` coil beinglocated inthe annulajrspace between-the heater elements Rand thecasing ";wall'will-b e subjected throughoutits `entire helicallength to Vthefradially Vradiated heat,`

ot any desiredintensizy,` said heat being ydis- *tribu'ted by thevheater-:over the entireannuf larspace, but the-foil willnot becomecarbonized because-,of its rapi'dflow in4 the pipe,

wh'i-lfethe heating r effect .of the heater ele-i fmentswill bev.limited by afthermostatrin the boXfjSf at ,the voutflow "end of theJVpipecoil where it is-subjected to the temperature ofrfthe outgoing oil.,An linstrument-box Q,

n on the outsidefwal-l Yofthe casing contains' the electrical:control-switches;meters` and connection-terminals.- lI? have not'shown'y herein-the thermostat and the-,electrical details, nor thedriving motor -for' the` pump, p.

sincek these may be ofcany suitable known construction Ijha-ve, however,shown 1n av ,separateapplication for kpatent al desirable system ofelectrical control Vforthis Oiltank -andfo'ther ta-nk'sfof Aa similar'type). I call particular attention tothe fact that the heating-ofthe oil-is 'carried on outside of andV independentlyof the body` of oilv:'ln'ather'trank.` Thusthe(utilization-ofthe heated oil in thevtempering or treatment of the metal articles fis notfafectedby thechangesand variationsin temperaturel incident to thel opera.-

.pering liquid,A a:

tion, of securing and maintaining the oil temperature and keeping it`constant and' uniform. vThe latter operation is a separate Y andindependent' one7 carried'onby itsown peculiaruneans fin awaytoadequately prepare the oil for its subsequent tempering oranalogous function in the bath.

llifhilel am claiming herein the above described apparatus and methodfor heat-- ing ol,vi,t isto be regarded as-only a specific T embodimentotga more (fundamental method ofheating; liquids, such 'as-"oils,Syrups, and

chemicalstliat-f are liable to damage bya` momenta'ryor'local excess oftemperature.

Thus it is diicult, if not impossiblafto avoid in ordinaryvflainefheaters',but can be avoided .witlrcertai-ntyby 'my method,while,"fin' addition, the whole body of liquid israised to its desiredmaximum temperature at the maximum' Vrate-fbecaus'e the heating isapplied vf to succeeding' quota'sv'of the masswithin a r region that isheated uniformly' throughout by'radiated'electrical heat." The volume ofythe quota in a given time .is dependent-,on the controlledvelocity ofljlovt'f.l`v For x'illus-"9"- tration, my method hasbeen adopted 'bythe'De Laval Separator Company tof/preheat transformer oilfbeforeclarifying vit by `centrffugal separators. Suchfoil' is 'susceptibletocarbonization which it is :vitally important to. avoid because -it`impairs Vits jelec- .trica-l insulating `.qu`ality. v'In that operationthe tcriticaly ratio between vthe three 'iac'tors of (heat energy, unitySuraCearea, and unit volumepe'rztimeunit, is foundto be 1000 gallons ofoil per hour, 'al lgiea'ter coil of'one and one-.quarter incl-1outside'diameter and nine lwatts' per square inch ofheatiiig surface.

i on

like manner-'the critical conditions ttor y i any similaliquid'f maybedeterminedf and mai'ntai'ned;k witli-"speed and certainty. fThe `the.heating eliiect can beideterminedwith accuracy andl the'heating effectcanbecontrolled with equalf` accuracy. 'Moreover, the perfectvminglingcreates. a mass vof uniform temperature under/certain andexactvcontrol.

l liVhatI claim "a's'hew 2 and desire to lSecure by'Letters'Batent is:v`7

l. lA'fterriper'ing .appa-ratus for the treatment of ,metallic articles'comp risingv a'heatinsulated 'Vreceptacle for; containinga -ternsec'ondj heatinsulated receptacle, a lliquid, heatingv coily Y within thesecond receptacle, means also "within the last mentioned `receptacle forheating said coil by radi'atedelectrical heat, and ,means forlcirculating vsaid tempering 'liquidithrough said 'coiland' also throughthe first mentioned receptacle consecutivelyso astio preventaJ-substantial drop in .temp eratureVy` "of j 'said liquid f2?, temperingapparatus 'forithe treatment of metallic articles comprising Ya heat-Vinst'ilateil receptacle liavinganv 'inflow' compartment 'a'ndaii"outflow "compartment,

uns p,

' volumeftliaftv is .at each ,moment subjected to y means by whichliquid in the inflow compartment is caused to overflow into said outflowcompartment, means within the inflow compartment for supporting thearticles to be tempered, a heating coil, a conduit extending from theheating coil to the inflow compartment, a second conduit extending fromthe outflow compartment to said coil, and means for positively impellingsaid liquid.

3. A tempering apparatus for the treatment ofnietallic articlescomprising a heatinsulated receptacle for containing a tempering liquid,a second heat-insulated receptacle, a liquid heating coil within thesecond receptacle, means also within the last mentioned receptacle forheating said coil, an endless conveyor so positioned in the firstmentioned receptacle that it will be submerged by said tempering liquid,a supply conduit extending from said heating coil and having itsdischarge end located in the space enclosed by said conveyor, `means forsupplying tempering liquid to said coil from the first mentionedreceptacle, and means for positively impelling said liquid.

4. A tempering apparatus for the treatment of metallic articlescomprising a heatinsulated receptacle provided with an inflowcompartment and an outflow compartment divided by an overflow7partition, an endless conveyor located in the inflow compartment so asto support the articles to be tempered, a heating coil, a conduitleading from said heating coil and discharging in the space enclosed bysaid conveyor, a second conduit leading from the outflow compartment tosaid heating coil, and means for positively impelling said liquid.

5. A tempering bath for metallic articles or a similiar liquid bodycomprising a heatinsulated receptacle having two separate compartmentscommunicating respectively with the inflow and outflow pipes from anelectrically heated container, and a screen in one compartment acrossthe route of the heating medium leading to the outflow pipe from thebath.

6. A tempering bath for metallic articles or a similiar liquid bodycomprisin a heatinsulated receptacle, inflow and out ow pipes for saidreceptacle communicating with an electrically-heated container for theliquid, a screen interposed between said pipes so that the said mediumwill flow therethrough, and means for maintaining a circulation of. theliquid through the heater and the bath consecutively.

7. A liquid-heating apparatus comprising a receptacle for the liquid anda separate heater receptacle, means within the first mentionedreceptacle for moving articles through said liquid, a pipe-coil in theheater-receptacle connected with said liquid receptacle, a series ofdistributed electric heating elements for distributing the heat over theexternal surface of the coil and means for maintaining a flow of theliquid through said coil.

Signed at State of New 1926.

Albany, county of Albany, York, this 2nd day of Aug.,

LEE P. HYNES.

